JP2004202576A - Forging metal die with two parallel faces facing each other, designing method for the metal die, forging method and forged article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forging metal die which can produce forged articles with excellent forming accuracy and high quality, and can also reduce production cost. <P>SOLUTION: The forging dies consist of a combination of a lower metal die 22 and an upper metal die 21 to forge a metal material into a forged article, and the lower die 22 is assembled by interference fitting of a mother die 24 with an insert die 23, while the insert die 23 is a metal die arranged inside the mother die 24 having a forging cavity 26 in the center. The inside wall face enclosing the forging cavity 26 of the insert die 23 is composed of at least a set of faces almost parallel to the moving direction of the upper die 21. The interference fitting position is not less than 65 mm and its fastening margin is the product of the outer diameter of the insert die and the value not less than 0.003 so that the dimensional precision such as the degree of parallel of the outer peripheral profile can be improved. Thus, a post-working such as cutting work becomes unnecessary and the production cost can be reduced. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a forging die, a forged molded product, and a forging method, and more particularly to a forging die having two opposing parallel surfaces, a forged molded product using the die, and a forging method.

  As a molded product having at least a pair of outer shell shapes that are forged using a mold composed of an upper mold and a lower mold, and having planes substantially parallel to the movement direction of the mold, for example, FIG. There is a molded product with the shape shown. Here, the reference numeral 11 and the reference numeral 12 have a pair of two parallel parallel surfaces. Moreover, the code | symbol 11 surface and the code | symbol 12 surface are 1 set of surfaces substantially parallel with respect to the operation | movement direction of the upper die to forge.

  Conventionally, in order to obtain a molded product having such a shape, the extruded material or the like is cut and cut to obtain the parallelism of the required surface.

  On the other hand, forging can be used as the forming means. However, in the case of the manufacturing method by forging, in order to make it easier to discharge the forged molded product from the mold after forging, the upper part of the lower mold is positively spread outward with respect to the operation direction axis of the upper mold. That is, a mold having a draft angle is generally used. In addition, since the mold is elastically deformed by the load during forging, the upper part of the lower mold spreads outward, so that a draft is naturally generated in the product. As a result, the molded forged product had a shape with an expanded upper part. As described above, the two facing surfaces of the conventional forged product are in an angled state, and the required dimensional accuracy such as parallelism is insufficient, so that dimensional accuracy such as parallelism is obtained. Therefore, cutting was performed after forging.

  Moreover, even if a part of the forming hole of the forging die is formed in parallel, the die is deformed by a load during forging, and it is very difficult to manufacture a forged product having two parallel surfaces. there were. Further, as shown in Patent Document 1, an insert member having a forging cavity of a mold used for forging is divided and this insert member is tightly fitted with a reinforcing ring member from the outside. ing.

JP-A-7-178495

The conventional method of manufacturing by cutting has a problem in that the material yield is poor and the manufacturing cost is high because a large amount of cutting waste is generated, and thus it is necessary to increase the material weight relative to the product weight. Further, since a lot of work time is required for machining, the productivity cannot be increased.
On the other hand, in the case of using a forging manufacturing method, there is less cutting waste than the conventional manufacturing method, and the material yield and productivity are improved. In order to obtain a highly accurate parallel shape, it finally required cutting. Furthermore, in the forging die described in Document 1, the inner insert 22 and the outer insert 20 are fitted at the undercut portion to shorten the dimension of the inner insert in the fitting direction. There is no technical idea to accurately process the parallel surface of the forged product by adjusting the shrinkage fitting stress.

  The present invention has been made in view of such a situation, and it is possible to easily forge a forged molded product that does not require or reduces post-processing machining, has a good yield, has a reduced cost, and has a good quality. An object of the present invention is to provide a forging die that can be manufactured.

1) 1st invention for solving the said subject consists of a combination of the lower metal mold | die and an upper metal mold | die for forging the forging molded product from a metal raw material, and the said lower metal mold | die is a mother die and a nested mold | die. Is assembled by an interference fit structure, and the insert mold is a mold provided inside the mother mold and provided with a forging hole at the center, and an inner wall surface surrounding the forging hole of the insert mold Is composed of at least one set of surfaces substantially parallel to the operation direction of the upper mold, and the interference fit position is a position of 65 mm or more, and the fastening allowance is a value of 0.003 or more with the telescopic mold outer diameter. A forging die characterized by having a product value of

2) A second invention for solving the above-described problem is that the interference fit position is a square root of the product of the molding hole diameter and the mother die outer diameter in the interference fitting structure of the mother die and the nested die. The die for forging according to 1), which is a position of a product value with .1.

3) According to a third invention for solving the above-described problem, in the interference fitting structure of the mother die and the nested die, the structure of the surface where the mother die and the nested die are fitted has a structure in which the nested die is difficult to come off. The forging die as described in 1) or 2) above.

4) A fourth invention for solving the above-mentioned problems is characterized in that, in the interference fitting structure between the mother die and the nested die, the material of the nested die is harder than the material of the mother die. The forging die according to any one of 1).

5) In a fifth invention for solving the above-mentioned problem, the inclination of the surface substantially parallel to the operation direction of the upper mold is 0 to 0.5 degrees from the operation direction axis of the upper mold to the outer side of the molding hole. The forging die according to any one of 1) to 4), characterized in that:

6) A sixth invention for solving the above-described problems is that any one of 1) to 5) is characterized in that the surface average roughness Ra of the inner wall surface surrounding the molding hole is 0.05 to 25 μm. Or a forging die according to claim 1.

7) The forging according to any one of 1) to 6), wherein the seventh invention for solving the above-mentioned problem is characterized in that the surface of the inner wall surface surrounding the forming hole is subjected to nitriding treatment. It is a metal mold.

8) An eighth invention for solving the above-described problems is any one of 1) to 7), wherein the mother die and the nested die have a plurality of interference fitting positions in the interference fitting structure. The forging die described in 1.

9) A ninth invention for solving the above-mentioned problems is a forged product manufactured using the mold according to any one of 1) to 8).

10) A tenth invention for solving the above problems is a mold comprising a combination of a lower mold and an upper mold for forging a forged molded product from a metal material, and the lower mold is composed of a mother mold and a mother mold. A forging method using a mold in which a mother mold and a nested mold are assembled by an interference fit structure, including a nested mold that is disposed inside and has a forged molding hole provided in the center. The inner wall surface surrounding the forging hole of the telescopic mold is composed of at least one set of surfaces substantially parallel to the operation direction of the upper mold, and the interference fit position is a position of 65 mm or more. This is a forging method characterized in that a metal mold whose value is the product of the outer diameter of the nested mold and a value of 0.003 or more is used.

11) An eleventh invention for solving the above problems comprises a combination of a lower mold and an upper mold for forging a forged molded product from a metal material, wherein the lower mold includes a mother mold and a nested mold. Is a mold design method in which the insert mold is disposed inside the mother die and a forging hole is provided in the center portion thereof,
The inner wall surface surrounding the forging hole of the insert mold is configured as at least one set of surfaces substantially parallel to the operation direction of the upper mold, and the interference fit position is 65 mm or more, and the tightening margin is The mold design method is characterized in that the mold is designed to have a product value of a nested mold outer diameter and a value of 0.003 or more.

12) A twelfth invention for solving the above problems comprises a combination of a lower mold and an upper mold for forging a forged molded product from a metal material, wherein the lower mold includes a mother mold and a nested mold. Is a mold design method in which a forging hole is provided in the center and a forging hole is provided in the center, and the forging hole is surrounded by the interference fitting structure. The inner wall surface is configured as at least one set of surfaces substantially parallel to the operation direction of the upper mold, and the shrinkage fit stress between the mother die and the nested die is (1 / 0.3) × (−200 × The mold design method is characterized in that the interference fit position and the allowance are designed so that the ratio of the insert mold forming hole to the outer diameter of the mother die is equal to or larger than 160).

13) According to a thirteenth invention for solving the above-mentioned problem, when designing the interference fit position and the allowance, first, when the shrinkage stress value is calculated and this value is equal to or greater than a predetermined value, it is the first time. The mold design method according to claim 12, wherein a mold deformation amount is calculated.

  The forging die of the present invention is a forging die composed of a combination of a lower die and an upper die for forging a forged molded product from a metal material, and the lower die is disposed inside the mother die and the mother die. A forging die in which the mother die and the nesting die are assembled by an interference fit structure, and the nesting die is forged. The inner wall surface surrounding the forming hole is composed of at least one set of surfaces substantially parallel to the operation direction of the upper mold, and the interference fit position is a position of 65 mm or more. Since this is a forging die characterized by a product value of 0.003 or more, in a molded product forged using the die, it is parallel to the operation direction axis of the upper die included in the outer shell shape. In order to obtain dimensional accuracy such as parallelism of at least a pair of opposing two surfaces on a smooth surface It is unnecessary or reduced.

  As a result, by using the forging die of the present invention, it is possible to easily produce a forged molded article having good dimensional accuracy such as parallelism of the outer shell shape. In addition, since a machining process that provides high accuracy by machining, which is a subsequent process, is unnecessary or reduced, the production cost can be reduced. Furthermore, since it has sufficient internal stress, the mold life can be extended.

  Further, according to the forging method using the forging die of the present invention, a forged product having two parallel parallel surfaces can be manufactured with high dimensional accuracy and at low cost.

  The purpose of the interference fit position is to obtain a forging die that can easily forge a forged molded product that does not require or reduces post-processing machining, has a good yield, reduces costs, and has good quality. This is realized by the position of 65 mm or more and the tightening margin being a product value of the nested outer diameter and a value of 0.003 or more.

  An example of a forging die according to the present invention will be described below with reference to the drawings. Here, the forging die 10 of the present invention comprises a combination of a lower die 22 and an upper die 21 for forging a forged molded product from a metal material. The mold 23 is assembled by an interference fitting structure, and the insert mold 23 is a mold provided inside the mother mold 24 and provided with a forging hole 26 at the center. The inner wall surface surrounding the forging hole 26 is composed of at least one set of surfaces substantially parallel to the operation direction of the upper mold 21, and the interference fit position is 65 mm or more, and the allowance is a nested mold. It is a product value of the outer diameter and a value of 0.003 or more.

  For example, as shown in FIG. 1, a cross section perpendicular to the operation direction axis of the upper mold having an outer shell surface 11, 12 parallel to the operation direction axis of the upper mold (outer shell surface). ) 13 is a forging die used for forging a forged molded product having a square shape. The fact that the inclination of the two opposing surfaces is 0.5 degrees or less from the operating direction axis of the upper mold to the outside direction of the molding hole is a mold part corresponding to reference numerals 11 and 12 in FIG. , 15 is 0.5 degrees or less.

  An example of the forging die of the present invention will be described with reference to FIG. The forging die 10 includes an upper die 21 formed of a pressure punch that moves up and down, a nested die 23 that constitutes a lower die 22 that receives a forging material, a mother die 24, and a molded product as a lower die 22. It includes a knockout pin 25 for taking out from the inside. Further, the insert mold 23 has a forming hole 26 in the center thereof, and the inner peripheral walls 26a and 26b corresponding to the forged product outer shell surfaces 11 and 12 of the forming hole 26 are 0 to 0 in the outer direction. It is formed at 5 degrees. The mother die 24 and the nested die 23 are assembled by an interference fit structure.

  Here, the interference fitting structure is assembled as follows, and will be described with reference to FIG. First, the outer matrix 24 is thermally expanded by heating. In the expanded state, the nested mold 23 is inserted inside the mother mold 24. Thereafter, the temperature of the matrix 24 is lowered to room temperature. As a result, the matrix 24 that has been thermally expanded is released from the thermal expansion and the nested mold 23 is tightened. As a result, internal compressive stress is generated in the nested mold 23.

  On the other hand, when combining forging dies conventionally, the fastening allowance is about 0.07 to 0.09 mm when the outer diameter H of the insert mold 23 is up to 30 mm, 0.15 to 0.18 mm up to 120 mm, Up to 180 mm was designed to be about 0.17 to 0.20 mm. This is disclosed, for example, in Press Technology (published by Nikkan Kogyo Shimbun), Vol. 39, No. 11, p. 74. Further, the tightening margin value can be obtained from the actually measured value by ((H−J) / 2). Here, H is the length of the outer diameter of the nested mold 23 in the state before the combination, and J is the length of the inner diameter of the mother die 24 in the state before the combination.

  In general, the boundary position between the nested mold and the mother mold when combined with an interference fit structure is called an interference fit position, and is expressed by a diameter centered on the center of gravity of the molding hole. When the boundary between the nesting mold and the mother mold is not a circle, for example, when the shape of the nesting mold is a regular polygonal cylinder, the inscribed circle of the nesting mold centered on the center of gravity of the section of the molding hole That's it. For example, this is indicated by reference numeral 27 in FIG. Conventionally, this interference fit position has been determined by trial and error.

  On the other hand, the forging of the present invention in which the inner wall surface surrounding the forming hole is composed of at least one set of surfaces substantially parallel to the operation direction of the upper mold and the mother die 24 and the nested die 23 have an interference fit structure. In the metal mold 10, for example, the interference fit position 27 is 65 mm or more, and the tightening margin is a product value of the nested mold outer diameter and a value of 0.003 or more (preferably 0.003 to 0.005). Can be obtained as a design. For example, the outer diameter of the telescopic mold is preferably 130 mm, the interference fit position is 130 mm, and the interference is preferably 0.39 mm or more. Further, the interference fitting position 27 of the telescopic mold is a product of the square root of the product of the forming hole diameter (G) and the outer diameter of the mother die (D) and 1 to 1.1 (hereinafter expressed by the equation 1). What is the forging die which becomes is preferable. When the contour shape of the cross section of the forming hole is not a circle, for example, when it is a rectangle, the diameter of the circumscribed circle of the contour shape is used as the diameter of the forming hole. Alternatively, when the contour shape of the outer shape of the mother die is not a circle, for example, when it is a regular polygon, the diameter of the inscribed circle of the contour shape is used as the outer diameter of the mother die.

  When the tightening margin is a product value of the nested outer diameter and a value less than 0.003, the internal stress is low and the inclination of the two opposing surfaces is large. In addition, the surface of the molding surface may be wavy or curved. When the interference fit position 27 is a value obtained by multiplying the square root of the product of the molding hole diameter G and the mold outer diameter D by a value less than 1, the thickness of the telescopic mold is reduced with respect to the internal stress, and the mold is formed. Damage may occur. Further, when the value obtained by multiplying the square root of the product of the forming hole diameter G and the outer diameter D of the die by a value exceeding 1.1, the thickness of the mother die is reduced with respect to the internal stress, and the forging die is formed. Damage may occur. Therefore, the product obtained by multiplying the square root of the product of the molding hole diameter G and the outer mold diameter D by a value in the range of 1 to 1.1 is preferable. Note that the interference fit position 27 is 65 mm or more (preferably 65 to 150 mm). If the interference fit position is set to less than this, the thickness of the nested mold is reduced with respect to the internal stress, and the mold is This is because damage may occur.

As a result, in the forging die 10 of the present invention, the internal stress is sufficiently large to prevent the parallel surface surrounding the forming hole 26 from opening outward during molding, as compared to the conventional forging die. It becomes the forging die which it has. FIG. 4 shows the relationship between the internal compression stress (hereinafter also referred to as shrink fitting stress) with respect to the ratio of the outer diameter of the mold of the present invention and the conventional mold to the outer diameter of the mother mold. “Ratio of molded product outer diameter to mold outer diameter” (where “molded product outer diameter means the same as“ molded product outer diameter ”or“ nested mold molding hole diameter ”) is used as a parameter. This is because the stress can be examined with a similar shape, and the result can be applied universally when the shape of the forging device or the molded product changes. As shown in FIG. 4, in the range of the ratio of the outer diameter of the product and the outer diameter of the master die in the range of 0.2 to 0.5, the present invention can apply a higher shrinkage stress than the conventional one. If it is less than this range, the molded product becomes too small, and if it exceeds this range, the mother mold tends to break, and it is practical and preferable to carry out within this range.

  For example, when the ratio of the outer diameter of the product to the outer diameter of the die is 0.2, as an example of the forging die of the present invention, the outer diameter of the mother die (circular) is 200 mm, the outer diameter of the product (the inner diameter of the insert mold forming hole) ) 40 mm, nested type (circular) outer diameter 90 mm, shrink fit 0.27 mm, the shrink fit stress is 400 MPa. In this case, the interference fit position is 90 mm which is the outer diameter of the nested mold, which is obtained by multiplying the square root of (product outer diameter (40 mm) × mother mold outer diameter (200 mm)) by 1.00. In this case, the fastening allowance (shrink fit allowance) is obtained by multiplying the nested outer diameter (90 mm) by 0.0030.

On the other hand, as an example of a conventional forging die obtained by the above-described design when the ratio of the outer diameter of the product to the outer diameter of the die is 0.2, the outer diameter of the mother die (circular) is 240 mm, the outer diameter of the product is In the case of the child mold forming hole circumscribed circle diameter) 48 mm and the nested mold (circular) outer diameter 107 mm, the shrinkage allowance was 0.18 mm and the shrinkage fit stress was 220 MPa. In this case, the interference fit position is 107 mm which is the outer diameter of the nested mold, which is obtained by multiplying the square root of (product outer diameter (48 mm) × mother mold outer diameter (240 mm)) by 0.99. In this case, the fastening allowance (shrink fit allowance) is obtained by multiplying the nested outer diameter (107 mm) by 0.0017.
Similarly, for example, when the ratio of the product outer diameter to the mold outer diameter is 0.3, as an example of the forging die of the present invention, a mother mold outer diameter of 200 mm, a product outer diameter (nested mold forming hole diameter) of 60 mm, When the outer diameter of the nested mold is 110 mm and the shrinkage allowance is 0.33 mm, the shrinkage fitting stress is 320 MPa. On the other hand, as an example of a conventional forging die obtained by the above-described design when the ratio of the product outer diameter to the mother die outer diameter is 0.3, a mother die outer diameter of 240 mm, a product outer diameter (nested die molding) Assuming that the hole diameter was 72 mm, the nesting outer diameter was 131 mm, and the shrinkage allowance was 0.2 mm, the shrinkage stress was 160 MPa.

  Similarly, for example, when the ratio of the product outer diameter to the mold outer diameter is 0.4, as an example of the forging die of the present invention, a mother mold outer diameter of 200 mm, a product outer diameter (nested mold forming hole diameter) of 80 mm, When the outer diameter of the nested mold is 127 mm, the shrinkage allowance is 0.38 mm and the shrinkage stress is 260 MPa. On the other hand, as an example of a conventional forging die obtained by the above-described design when the ratio of the product outer diameter to the mother die outer diameter is 0.4, a mother die outer diameter of 240 mm, a product outer diameter (nested die forming hole diameter). ) When the inner diameter was 96 mm and the outer diameter of the nested mold was 151 mm, the shrinkage allowance was 0.2 mm, and the shrinkage stress was 110 MPa. As an example of another conventional forging die obtained by the above-described design when the ratio of the outer diameter of the product to the outer diameter of the master die is 0.4, the outer diameter of the master die is 103 mm, the outer diameter of the product (nesting die molding). Assuming that the hole diameter was 41 mm, the nested mold outer diameter was 65 mm, and the shrinkage allowance was 0.18 mm, the shrinkage fitting stress was 240 MPa.

  Similarly, for example, when the ratio of the product outer diameter to the mold outer diameter is 0.5, as an example of the forging die of the present invention, a mother mold outer diameter of 200 mm, a product outer diameter (nested mold forming hole diameter) of 100 mm, If the outer diameter of the nested mold is 142 mm and the shrinkage allowance is 0.43 mm, the shrinkage fitting stress is 200 MPa. On the other hand, as an example of a conventional forging die obtained by the above-described design when the ratio of the product outer diameter to the mother die outer diameter is 0.5, the outer diameter of the mother die is 240 mm, the outer diameter of the product (nesting die forming hole diameter). ) In the case of 120 mm and the insert type outer diameter of 169 mm, the shrinkage allowance was 0.2 mm and the shrinkage stress was 80 MPa. Thus, in the forging die 10 of the present invention, the shrinkage stress is larger than that of the conventional forging die in any ratio of the outer diameter of the product and the outer diameter of the master die, and the upper part of the product is forged during forging. It turns out that it is preferable at the point which can suppress spreading to an outer side direction.

  In the present invention, for example, the outer diameter of the mother die = 200 mm, the dimensions of the two opposing surfaces of the molding hole = 42 mm, and the circumscribed circle diameter of the molding hole is 60 mm. The circumscribed circle diameter is applied to G.) The outer diameter of the nested mold is 110 mm and the interference fit position is 110 mm. The longitudinal elastic modulus and Poisson's ratio of the matrix (material SKD61) and the nested mold (material SKDll) are 202 GPa, 200 GPa, 0.3, and 0.3, respectively. In the forging die 10 of the present invention, for example, the tightening margin is set to 0.39, so the stress generated by the interference fitting structure is 320 MPa. The forging die 10 of the present invention can load a stress about twice or more that of a conventional forging die.

  The calculation formula of shrink fit stress is, for example, Mechanical Engineering Handbook (4th edition issued by the Japan Society of Mechanical Engineers), 4th edition, Material Mechanics, Chapter 8 Cylinder, Sphere and Disc 8.6 Combination Cylinder, and Shrink Fit 8.6.1. It is disclosed in a thick combination cylinder ("4-73" page).

On the other hand, in the forging die designed by the conventional method, the tightening margin is 0.18 from the above-mentioned empirical value, so the stress is 180 MPa, and the forging die opens to the outside during forging and has a parallel surface. Molded product cannot be obtained. Since the forging die of the present invention has an internal stress sufficient to prevent the parallel surface from opening outward during molding, the forging die has no draft even during forging. Become a mold. When a forged product is produced using this, deformation of the forging die is suppressed during forging. As a result, it is possible to easily and accurately manufacture a forged product having an outer shell shape composed of a surface substantially parallel to the operation direction of at least one set of upper molds.
In the mold according to the present invention, the shrinkage stress satisfying [Equation 2] is more preferable when the “ratio of the insert mold forming hole and the outer diameter of the mold” is in the range of 0.2 to 0.5. preferable. This is because a mold having two parallel surfaces can be easily obtained by designing the mold to satisfy this condition.

  This is a range equal to or greater than a straight line passing through two points (0.2,400) (0.5,200) in FIG.

  Furthermore, although the interference fitting place is one place, it may be two or more. For example, when the mother die 24 is composed of an inner mother die and an outer mother die, and the nested die 23 is comprised of an inner nested die and an outer nested die, The interference fit position is determined by the method of the present invention described above between the child mold and the outer insert mold, and then the interference fit position is determined by the method of the present invention between the outer insert mold and the inner mother mold. Further, an interference fit position is determined between the inner matrix and the outer matrix by the method of the present invention. By the above procedure, a plurality of interference fit positions are sequentially determined. Furthermore, in the forging die of the present invention, a part of the operation direction length of the upper die on the inner wall surface surrounding the forming hole may be a parallel surface, or the entire operation direction length may be May be parallel surfaces.

  In the forging die of the present invention, in the interference fitting structure between the mother die 24 and the nested die 23, the shape of the fitting surface of the mother die 24 and the nested die 23 is such that the nested die is difficult to come off. preferable. For example, FIG. 3 illustrates a forging die having a shape in which the outer diameter H and the inner diameter J of the nesting die are straight, but the shape of the outer diameter of the nesting die and the inner diameter of the dies is the upper mold operation direction axis. It may have a tapered shape with a conical shape in the vertical direction.

  5 (a) to 5 (c) are longitudinal sectional views of main parts showing other embodiments of the present invention. FIG. 5A shows another embodiment showing an interference fitting structure between the telescopic die 23 and the mother die 24 in the present invention. In the present embodiment, the outer diameter H of the telescopic mold 23 and the inner diameter J of the mother mold 24 are formed in a tapered shape that expands downward. When configured as described above, a structure in which the telescopic mold 23 is not easily removed can be obtained.

  FIG. 5B is another embodiment showing an interference fitting structure between the telescopic die 23 and the mother die 24 in the present invention. In the present embodiment, the outer diameter H of the nested mold 23 and the inner diameter J of the mother mold 24 are formed in a tapered shape that is reduced downward. When configured as described above, since the pressing force by the upper mold 21 can be received by both the insert mold 23 and the mother mold 24, the useful life of the forging mold 10 can be extended.

FIG. 5 (c) shows another embodiment showing an interference fitting structure between the telescopic mold 23 and the mother mold 24 in the present invention. In the present embodiment, the outer diameter H of the insert mold 23 and the inner diameter J of the mother mold 24 are formed in a tapered shape, and the ring presser 51 is fixed by a bolt 52.
When configured as described above, since the pressing force by the upper mold 21 can be received by both the insert mold 23 and the mother mold 24, the service life of the forging mold 10 can be extended, Even if the nested mold 23 warps and acts as a repulsion, the nested mold 23 can be prevented from coming off.

FIG. 6A is a cross-sectional view showing another embodiment of the relationship between the nested mold and the mother mold of the present invention. In the present embodiment, a step portion 61a is formed at the upper end, which is a part of the outside of the telescopic die 61 in which the molding hole 26 is formed. In FIG. 6A, the step portion 61 a includes an annular recess formed on the outer periphery of the upper end of the telescopic die 61 and an annular protrusion formed on the inner periphery of the corresponding mother die 62.
In the case of the above configuration, the nested mold 61 and the mother mold 62 are engaged with each other at the step portion 61a, so that there is no possibility that the nested mold 61 comes out.

FIG. 6B is a cross-sectional view showing another embodiment of the relationship between the nested mold and the mother mold of the present invention. In the present embodiment, a step portion 65a is formed on a part of the outer side of the telescopic die 65 in which the molding hole 26 is formed. In FIG. 6B, the step portion 65 a is configured by an annular protrusion formed on the outer periphery of the lower end of the telescopic die 65 and an annular recess formed on the inner periphery of the lower end of the corresponding mother die 66.
In the case of the configuration as described above, the nested die 65 and the mother die 66 are engaged with each other at the step portion 65a, so that the nested die 65 does not come out.

  The forging die 10 of the present invention uses a member in which the hardness of the material of the mother die 24 and the inner die 23 is higher in the inner die 23 in the interference fitting structure of the mother die 24 and the inner die 23. It is preferable. This is because, when the forging die 10 is combined, the insert die 23 can be press-fitted without damage. In the forging die 10 of the present invention, the material of the insert die 23 is preferably die steel (for example, JIS SKD11) (more preferably, high-speed steel or cemented carbide). When mild steel is used, elastic deformation increases, and when this is used to forge a molded product, it is easy to taper. Moreover, it is because there exists a possibility that a wave | undulation and curvature may generate | occur | produce on a molding surface.

  In the forging die 10 of the present invention, the surface average roughness of the inner wall surface surrounding the molding hole 26 is more preferably Ra = 0.05 to 25 μm (more preferably 0.05 to 1.6 μm). If the thickness is less than 0.05 μm, it is difficult to ensure accuracy during die processing, and if it exceeds 25 μm, the material is seized during forging.

  In addition, the forging die 10 of the present invention is preferably subjected to nitriding treatment on the surface of the inner wall surface surrounding the forming hole 26. As a result, in the process of discharging the molded product from the lower mold 22, when the molded product and the lower mold 22 come into contact with each other, it is possible to suppress the occurrence of defects such as seizure or galling and poor surface accuracy. Because it can. Moreover, it can suppress that it becomes a starting point of a crack by the load applied at the time of forging in the location where the seizure or galling occurred, and the durable life of the forging die can be improved.

  The forging die of the present invention can be used in a conventional forging method regardless of warm forging or cold forging. Various metal materials can be used as the forging material. For example, aluminum, iron, magnesium, and alloys based on these can be given. As the aluminum alloy, for example, JIS6061, 2017 alloy or the like can be used.

Next, the basic flow of the mold designing method of the present invention will be described.
1) First, when a shape of a molded product is given, an apparatus to be used is determined from its size, and an outer diameter D of the mother die is determined from a mother die attached thereto.
2) Subsequently, the molding hole diameter G is obtained from the size of the molded product.
3) Next, the interference fit position is determined based on Formula 1 so as to be 65 mm or more from the molding hole diameter G and the outer diameter D of the mother die. The coefficient is determined temporarily.
4) Next, the interference fit position is set as the telescopic outer diameter H, and a factor of 0.003 (tightening factor) is multiplied by this to obtain a fastening margin.
5) This completes the initial design of the mold.
6) An actual mold is manufactured based on the initial setting, and forging is tried.
7) If a problem such as not satisfying the parallelism, flatness, etc. occurs, gradually increase the interference coefficient from 0.003 and repeat the process from 4) to confirm that the problem disappears.
8) If the problem of 7) does not go away, adjust the interference fit position and repeat the steps from 3) to confirm that the problem disappears.
9) The mold design is completed as described above.
Furthermore, from FIG. 4, it is shown that the shrinkage stress satisfies [Equation 2] with respect to the ratio 0.2 to 0.5 between the nested mold hole G and the outer diameter D of the mold 4). By confirming at this time, it can be set as the metal mold | die which suppressed that a shaping | molding hole opens outside in a parallel site | part. The molded product forged using the mold is processed to obtain dimensional accuracy such as parallelism of at least a pair of two opposing surfaces in a plane parallel to the operation direction axis of the upper mold included in the outer shell shape. Is preferable because it is unnecessary or reduced.

Next, a case where a mold having a complicated shape is designed by the mold design method of the present invention will be described.
An example of a molded product in the case of a complicated mold is shown in FIG. The molded product shown in FIG. 9 has a shape in which two different parallel surfaces are combined with a step.
This is an example of a molded product provided with outer shell surfaces 91 and 92 parallel to the operation direction axis of the upper mold and similarly parallel outer shell surfaces 91a and 92a having steps thereon. Here, the basic design concept is the same as described above, but in the case of a mold partially having a shape parallel to the main molding direction, or the cross section of the molded product is combined with irregularities, and the cross section is circular. If inconvenience arises when designing by approximating the shape, it can be designed as follows.
For example, if you have a shape that is parallel to the main molding direction, apply the above-mentioned design to the cross section at the parallel part, and if you have multiple different parallel parts, The above-mentioned design is applied. Furthermore, it is preferable to design the mold so that they all satisfy the conditions of FIG. As a result, a molded product forged using the mold obtains dimensional accuracy such as parallelism of at least a pair of two opposing surfaces in a plane parallel to the operation direction axis of the upper mold included in the outer shell shape. This is preferable because processing is not required or reduced.

Also, by incorporating the simulation into the design, it is possible to reduce the man-hours for redesigning the mold. Next, an example of a design method incorporating a simulation will be described with reference to the flowchart shown in FIG.
First, in step S1, a basic design of a nested type and a shrink-fit shape is performed based on the experimental result of a simple shape. Here, the initial values of the shrinkage fit and the interference fit position are given by the above-described design with respect to the cross section at the parallel portion.
Next, a forging simulation is performed to obtain the mold shape.
The forging simulation used in the present invention has two stages: a molding simulation in step S2 and a mold deformation simulation in step S3. In step S2, the state in which the material put into the mold forming hole is molded is simulated, but the calculation time is shortened by treating the mold as a rigid body. In step S3, the mold is treated as an elastic body, and the surface force data of the molded product obtained from the result of step S2 is given to the mold, and the deformation of the mold when it is reflected is obtained by calculation.

  An FEM (finite element method) analysis can be used for the simulation. In FEM analysis, a boundary value problem formulated based on continuum mechanics is solved by numerical analysis using a computer. There are three basic formulas for boundary value problems: a constitutive equation representing the deformation characteristics of a forged product, a variational principle equation representing the balance of stress, friction with the mold, and a boundary condition equation representing contact. The degree of approximation and modeling method are selected in consideration of modeling. The FEM analysis includes (1) pre-processing for preparing and creating data used for the calculation, (2) execution of calculation based on the prepared data, and (3) post-processing for displaying and evaluating the result after execution of the calculation. The analysis procedure has three steps.

Specifically, the molding simulation in step S2 is performed as follows.
First, in the pre-processing in step S2, the following processes (a) to (d) are executed.
In S2 (a), forged product shape data is created.
Forged product CAD data is created faithfully based on the shape and dimensions of a given molded product (forged product) and used as shape data.
In S2 (b), simple mold shape data is created.
Next, simple mold shape data is created. Formed hole shape data is created from the shape obtained by inverting the forged product shape CAD data using CAD Boolean calculation, and divided and processed based on a punch and die shape designed separately in advance to create shape data. The shape data of the portion not in contact with the inner surface of the forged product may be generated approximately within a range that does not affect the calculation. In addition, the shape data is created as an integral part of nesting and shrink fitting.
In S2 (c), material shape data is created.
Next, material CAD data is created based on a material shape and dimensions separately designed in advance and used as shape data.
In S2 (d), the shape data of (a) to (c) are taken into the calculation data store unit and used as analysis shape data. Further, the following data is set as the molding condition parameter. For example, the amount of movement of the punch, the moving speed, the timing, the position setting between the raw material and the mold, the friction condition, the molded product material characteristic value (stress-strain relationship), and the material temperature.
In the case of warm forging, it is preferable to add the mold temperature, heat transfer coefficient, and thermal conductivity to the setting conditions.

  Next, in the calculation execution stage of step S2, a nonlinear finite element method program is executed and calculated based on the data created by the pre-processing of (a) to (d). The forging process is simulated by executing the program, and finally the force that the molded product gives to the mold is obtained as data. In step S2, the post process may be a process of checking the calculation result, and no further process is required. It is preferable to add a confirmation process for molding defects.

Specifically, the mold deformation simulation in step S3 is performed as follows. First, in the pre-processing in step S3, the following processes S3 (e) to (g) are executed.
In step S3 (e), actual mold (nested / shrink fit) shape data is created. Formed hole shape data is created from the shape obtained by inverting the forged product shape CAD data created in step S2 (a), and the nesting / shrink fit shape CAD data is generated based on the nesting / shrink fit shape designed in step S1. Create and import into the calculation data store section to obtain shape data for analysis.
In step S3 (f), a mold surface boundary condition is set. In the coordinate space inside the calculation data, the actual mold shape data created in S3 (e) is arranged at the same position as the molding simulation in step S2, and the surface force data of the molded product included in the molding simulation result in step S2 is obtained. It is given as a boundary condition.
In S3 (g), the following data is set as a condition parameter.
Position setting between nesting and shrink fitting, friction conditions, tightening allowance, mold material characteristic values (elastic modulus, Poisson's ratio), nesting and shrink fitting fixed boundary conditions, and constraint conditions are set.

Next, in the calculation execution stage of step S3, the die deformation is performed by executing a nonlinear finite element method program or a linear finite element method program based on the data created by the pre-processing of S3 (e) to (g). Simulate.
When a linear finite element method program is used, mold material characteristic values (elastic modulus, Poisson's ratio) are set. When the nonlinear finite element method program is used, characteristic values of the plastic region, that is, stress-strain relationship data are set.

In post-processing, mold deformation is investigated from the calculation results. Since the molded product is a reversal shape of the mold, the shape of the molded product can be investigated from the deformation of the mold.
As described above, the shape state of a molded product can be investigated by FEM analysis.
Next, in step S4, first, it is determined whether or not the molding shape defect (for example, parallelism, flatness) falls within an allowable value. A simulation under the same conditions as the experiment for a simple shape has already been carried out, and the relationship between the shape defect occurring in the experimental molded product and the calculated mold deformation amount is quantitatively grasped. Referring to this relationship, if it is determined that a shape defect will occur, the process proceeds to step S5.

  In step S5, when it is determined that the shape defect can be avoided by changing the tightening allowance, an increase amount of the tightening allowance is set, and the process returns to step S3 again. In step S3, it is only necessary to change the tightening value of S3 (g), and no other change is necessary. If it is determined that the defective shape cannot be avoided by changing the tightening allowance, the process moves to step S6 to consider changing the actual mold shape. The parameter is the tightening position. After the shape change, the process returns to step S3 (e), the actual mold shape data is recreated based on the actual mold shape changed in step S6, and the mold deformation simulation in step S3 is performed. When it is determined in the next step S4 that no defective shape of the molded product occurs, the forging die design is finished.

  Before step 3, it is preferable to provide a step (step S3A) of calculating the shrinkage stress of the actual mold. In step S3A, (f) is omitted by using the same process as in step S3, that is, the value of the molded product surface force is set to zero, and S3A (e) and S3 (g) are the same as in step S3 (e). A nonlinear finite element method program is executed on the basis of data created by the same pre-processing of S3A (g) to simulate mold deformation, and stress can be obtained by post-processing.

  When the shrinkage stress of the actual mold is obtained, it is preferable to include a routine for determining that the stress obtained in step S3A satisfies a predetermined condition. As the predetermined condition, the hatched portion in FIG. By inserting this determination routine, it is possible to determine whether the mold design state is acceptable or not before obtaining the deformation amount by simulation. Therefore, since the step S3 of the die deformation amount simulation calculation having a long calculation time can be omitted, the entire calculation time can be shortened. As described above, if necessary, step S3 of the deformation amount simulation calculation can be included for confirmation. If it is determined that the determination routine is not possible, it is preferable to execute step S3A again by changing the interference fit position and the value of the interference margin within a range that satisfies the above-described conditions.

The above method states that "firstly, the mold is used as a rigid body to solve the deformation of the molded product, the pressure on the mold is obtained, and then the pressure is applied to the elastic mold to solve the mold deformation". .
This method assumes that in aluminum alloy forging (especially warm forging), the deformation resistance between the aluminum alloy and the mold is different by about three orders of magnitude, so that the mold deformation is negligible compared to the deformation of the aluminum alloy. This calculation is preferable because the calculation time can be shortened. Since the accuracy of parallel surfaces is targeted, the meshing of the mold at the stage of the molding simulation can be omitted.

If the draft generated in the molded product due to the deformation of the mold is directly obtained by simulation, the draft shape is very small (for example, 1/1000) with respect to the size of the entire mold shape. As a result, the number of meshes becomes enormous and the computation time becomes enormous, which is not practical.
However, in the present invention, the stress may be calculated under the limiting conditions set in the tightening allowance and the interference fit position, and the mesh may be set so that two or more nodes hit the R-shaped portion. Can be greatly shortened. In addition, by including a routine for determining shrinkage stress, the calculation is performed while predicting the occurrence of draft, so that not only the calculation time can be shortened but also the accuracy of the calculation result can be improved.

  On the other hand, it may be necessary to consider the deformation of the mold during molding. For example, when a thin plate stands in the molding hole of a mold like a compressor rotor, the aluminum alloy of the material is covered with a load of several tens of tons from the thin plate during molding. Therefore, a part of the mold (for example, a thin plate) is deformed, and as a result, an influence is expected on the plastic flow state of the aluminum alloy. If the plastic flow state of the aluminum alloy is affected, the force on the mold will also be affected, and there may be a large error from the assumption that there is no deformation of the mold. Therefore, when designing a mold for a product having such a shape, it is preferable to use the method of “simultaneously solving the deformation of the mold and the molded product” in one step without using the two-step method as described above. preferable. At this time, it is preferable to sufficiently mesh the mold so that the deformation of the mold is required at the stage of the molding simulation. Even in such a case, the calculation time can be shortened by performing the calculation under conditions.

  Although the present invention will be described in detail below based on examples of the present invention, the present invention is not limited to these examples.

  In the present example, a hand component having an appearance as shown in FIG. 8 was manufactured using the forging die shown in FIG. Hand parts are used for chucking parts of industrial equipment and the like. The shape of the hand component is required to have an inclination of the 81 and 82 planes of 0.5 degrees or less with respect to the vertical plane. As the forging material, a JIS6061 aluminum alloy cast rod manufactured by a continuous casting method, which was formed into a column having a maximum width of 50 mm by hot extrusion, was further cut into a length of 24 mm.

  The forging die was assembled with an interference fitting structure with an outer diameter of the telescopic mold of 120 mm and an allowance of 0.36 mm (= the outer diameter of the telescopic mold (120 mm) × 0.003). The outer diameter of the mother mold = 240 mm, the dimension between the two opposing surfaces = 26 mm, and the circumscribed circle of the molding hole = 54 mm. The interference fit position was 120 mm. Since the mother die is made of material SKD61 and the nested die is made of material SKD11, the longitudinal elastic modulus and Poisson's ratio are 202 GPa, 200 GPa, 0.3, and 0.3, respectively. From the above, the shrinkage stress was 390 MPa.

  Further, the surface finish of the inner wall surface surrounding the forming hole was polished so as to be 1.5 μm in Ra. Further, the surface of the inner wall surface surrounding the forming hole was subjected to nitriding treatment. After applying the lubricant to the mold and the raw material, it was molded by warm forging with a forging load of 60 t. After forging, the hand parts forged with the knockout pin were sent out from the lower mold upward. As a result, the shape of the outer shell of the product was 0.3 degrees, the inclination of two faces facing each other in a plane parallel to the upper mold movement direction axis, which is 0.5 degrees or less, which is a preferable value. Furthermore, regarding the appearance, the forged product of this example did not show galling or seizure.

Another forging die according to the present invention has an interference fit structure in which the outer diameter H of the nested mold is 156 mm and the allowance is 0.47 mm (= the outer diameter of the nested mold (H: 156 mm) × 0.003). Assembled. The outer diameter of the mother die = D: 240 mm, the dimension between two opposing surfaces = 60 mm, and the circumscribed circle of the forming hole = 98 mm. The interference fit position was 156 mm. The material of the mother mold and the nested mold was the same as described above.
In the outer shell shape of the product, the inclination of two surfaces facing each other in a plane parallel to the upper mold movement direction axis was 0.3 degrees, which is 0.5 degrees or less, which is a preferable value. Furthermore, regarding the appearance, the forged product of this example did not show galling or seizure.

  For comparison, forging was performed using a conventional forging die. The telescoping position of the nested mold was a position having a diameter of 98 mm. The tightening margin was 0.18 mm. The shrink fit stress was 230 MPa. The surface finish of the inner wall surface surrounding the molding hole was 30 μm in Ra. Further, the surface of the inner wall surface surrounding the forming hole was not subjected to nitriding treatment. The material of the mother mold and the nested mold and other conditions were the same as in the examples of the present invention.

  When forging was performed using the forging die as described above, the obtained molded product had an inclination of a plane parallel to the upper mold operation direction axis of 0.7 degrees exceeding 0.5 degrees. In addition, galling and image sticking occurred with respect to the appearance.

  A mold for forging the molded product shown in FIG. 9 was designed by the simulation of the present invention. Forging was performed using a mold produced based on the design result. As a result of trial manufacture, it was possible to obtain a molded product having a draft of the parallel portion of 0.4 without correction. In addition, no galling or image sticking occurred with respect to the appearance.

  As described above, by using the forging die of the present invention, it is possible to improve the yield and reduce the cost by eliminating or reducing machining, which is a post-forging process. Further, a forged product having almost no draft can be easily forged.

  In the embodiment of the present invention, the example in which the ring presser is fixed to the mold by the bolt has been described. However, the present invention is not limited to this, and other fixing means may be used.

It is a perspective view which shows an example of the forge molded product which at least 2 surfaces which oppose are parallel. It is a principal part longitudinal cross-sectional view which shows an example of the forging machine used for the metal mold | die for forging of this invention. It is a schematic diagram which shows the relationship between the forming hole of a nested mold, and a mother mold. It is explanatory drawing which shows the relationship between the ratio of the product outer diameter by the invention for this application and the conventional forging die, a mother die, and shrinkage fitting stress. 5 (a) to 5 (c) are longitudinal sectional views of main parts showing other embodiments of the present invention. 6A and 6B are sectional views showing another embodiment of the relationship between the nested mold and the mother mold of the present invention. It is a principal part longitudinal cross-sectional view which shows an example of the forging machine used for the metal mold | die for forging of this invention. It is a perspective view which shows the hand component which is an example of a forge molded product. It is a perspective view which shows an example of the forge molded product which has the shape where two different parallel surfaces have a level | step difference, and were combined. It is a flowchart which shows an example of the design method incorporating simulation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Forging metal mold 11 Outer shell surface 12 Outer shell surface 13 Outer shell surface 14 Surface inclination 15 Surface inclination 21 Upper mold 22 Lower mold 23 Nesting mold 24 Mother mold 25 Knockout pin 26 Molding hole 27 Nesting mold Boundary position 51 of ring and mold 51 Ring retainer 52 Bolt 61 Nesting mold 61a Step 65 Nesting 65a Step 66 Mother 62 62 Master 81 Outer shell 82 Outer shell

Claims (13)

It consists of a combination of a lower mold and an upper mold for forging a forged molded product from a metal material. The lower mold is assembled by a close fitting structure between a mother mold and a nested mold, and the nested mold is a mother mold. A mold provided inside the mold and provided with a forging hole in the center,
The inner wall surface surrounding the forging hole of the telescopic mold is composed of at least one set of surfaces substantially parallel to the operation direction of the upper mold, and the interference fit position is 65 mm or more, and the tightening margin is A forging die characterized by having a product of the outer diameter of the nested die and a value of 0.003 or more. In the interference fitting structure of the mother die and the nested die, the interference fitting position is a square root of the product of the molding hole diameter and the mother die outer diameter, and a position of a product value of 1 to 1.1. The forging die according to claim 1. 3. The interference fitting structure between the mother mold and the nested mold, wherein a structure of a surface where the mother mold and the nested mold are fitted is a structure in which the nested mold is difficult to be removed. Mold for forging. The forging die according to any one of claims 1 to 3, wherein in the interference fitting structure between the mother die and the nested die, the material of the nested die is harder than the material of the mother die. The inclination of the surface substantially parallel to the movement direction of the upper mold is 0 to 0.5 degrees from the movement direction axis of the upper mold toward the outer side of the molding hole. 2. A forging die according to item 1. The forging die according to any one of claims 1 to 5, wherein the surface average roughness Ra of the inner wall surface surrounding the forming hole is 0.05 to 25 µm. The forging die according to any one of claims 1 to 6, wherein a nitriding treatment is performed on a surface of an inner wall surface surrounding the forming hole. The forging die according to any one of claims 1 to 7, wherein the base die and the insert die have a plurality of interference fitting positions in the interference fitting structure. A forged product manufactured using the mold according to any one of claims 1 to 8. A die composed of a combination of a lower die and an upper die for forging a forged molded product from a metal material. The lower die is disposed inside the mother die and the mother die, and a forging hole is provided in the center. A forging method using a mold in which the mother mold and the nested mold are assembled by an interference fit structure,
The inner wall surface surrounding the forging hole of the insert mold is composed of at least one set of surfaces substantially parallel to the operation direction of the upper mold, and the interference fit position is a position of 65 mm or more. A forging method characterized in that a mold having a product value of a mold outer diameter and a value of 0.003 or more is used. It consists of a combination of a lower mold and an upper mold for forging a forged molded product from a metal material. The lower mold is assembled by a close fitting structure between a mother mold and a nested mold, and the nested mold is a mother mold. A mold design method in which a forging hole is provided in the center and disposed inside the mold,
The inner wall surface surrounding the forging hole of the insert mold is configured as at least one set of surfaces substantially parallel to the operation direction of the upper mold, and the interference fit position is 65 mm or more, and the tightening margin is A mold design method, wherein the mold is designed to have a product value of an outer diameter of the nested mold and a value of 0.003 or more. It consists of a combination of a lower mold and an upper mold for forging a forged molded product from a metal material. The lower mold is assembled by a close fitting structure between a mother mold and a nested mold, and the nested mold is a mother mold. A mold design method in which a forging hole is provided in the center and disposed inside the mold,
The inner wall surface surrounding the forging hole of the nested mold is configured as at least one set of surfaces substantially parallel to the operation direction of the upper mold,
The interference fit position so that the shrinkage fitting stress between the mother die and the nested die is not less than (1 / 0.3) × (−200 × ratio of the nested die forming hole and the mother die outer diameter + 160) and A mold design method characterized by designing a fastening allowance. In designing the interference fit position and allowance,
First, the shrinkage stress value is calculated, and when this value is a predetermined value or more,
The mold design method according to claim 12, wherein the mold deformation amount is calculated for the first time.

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